Friday, October 17, 2014

Coffee Brake: What Is Fast?

If you are car guy and a speed junkie, you'll usually be looking for your next ride to be a bit faster.  You can look up factory 0-60 mph specs to get an idea of how it scoots off the line, or 1/4 mile trap speeds to see how it'll go at speed and if you want to know how it handles you can look up skid pad g-levels from magazines.  Unfortunately OE tire compound (which you are going to change anyway), gear ratios, measurement techniques and surface differences make many of these numbers worthless.  What you need is a good idea of how the car will run through a section of road with all external factors being equal.  One of the tricks I've used for a quick comparison of overall speediness is the SCCA Solo2 autocross Stock Classification.

The SCCA Solo2 car classification rules are available on the SCCA website, but the Mouton family website is a far better and easier to way to navigate by class (although the Moutons site hasn't been updated since 2011).  A few quick notes about "Stock" class in Solo2.  First, it allows R-compound tires, any shock absorber you want (including $10,000 remote reservoir setups), cat back exhaust, drilling/enlarging holes for camber adjustment and a front swaybar change.  That is about it.  Everything else must be 100% stock. Stock sized wheels, stock springs, stock engine, stock airbox -- you can read a nice list of Solo2 classing rules here on  Notice yet another piece of information is available on the web from a third party source -- not implying that the geezers running SCCA are totally inept at making the rules clear and easy...but...the straw hat crowd tends to enjoy sneering at newcomers and hazing them with nuances of a 363 page rule book.

Before you get too far into the details of the stock classifications, there are a few things to consider.  First, the classes are meant to provide a balanced racing environment, and class F isn't necessarily slower than class D.  For the most part, the fastest stock class times of the day will be set by Super Stock, next A, then B...etc.  Some cars are not allowed to run in Stock class because they are too fast, such as Audi R8, Lotus Exige SC, Nissan GT-R, all Lambos and Ferraris; Super stock is a class for cars that are naturally fast between the cones, Z06 Vettes, 997, 911 Turbo; A-Stock is the next step down in speed, C5 Vette, older Boxster S, RX-7 Turbo; B-Stock more sports cars and sports sedans, NSX, E46 M3, Evo, STi, Supra Turbo; C-Stock is the Miata class, but includes Z3 M Coupe/Roadster, 350Z, older 911, 914, MR2 Turbo; D-Stock is slightly slower, WRX, Integra Type R, 335i, R32; E-Stock is older Miatas, 240Z, non-turbo MR2, BMW Z3; F-Stock is for V8 sedans and will sometimes be faster than E-Stock, Mustang, S4, Camaro, M5; G-Stock is a catch all for cars that are slow, but not total piles of junk, VW GTi, Prelude, Taurus SHO, BMW 2002, Alfa GTV, and H-Stock is for everything else on 4-wheels that isn't on fire, Gremlin, Chevette, MGB, Mercury Lynx, Toyota Echo, Saab 99 etc.

Keep in mind that the cars listed in Stock class are cars with a strange setup of ultra sticky rubber and no rear sway bar, but many cars respond to a few grand in suspension. The next place to check is to see where cars end up when they are bumped up to the Street prepared or Street modified classes.  An STi will go from B-stock to B-Street prepared, while a basic WRX will move from D-stock to B-Street prepared because the WRX will gain more as it moves onto a stiffer suspension and wider wheels that the STi already has. 

So, what to do with this information?  Say you are looking to replace your daily driven STi with something equally fast and are considering the Audi B7 S4.  On paper, it looks to be a similar car, but it's classed down in F-stock compared to the STi's B-stock rating -- a big difference in terms to autocross competitiveness.  A better choice would be the C32 AMG if you were willing to live with an automatic transmission.  Is the Stock classification a big deal?  Probably not...but it adds one more piece of data for used car shopper and has never let me down in my search for fun modern street cars.

Got a better way to compare cars before the test drive? Comments below.


  1. people are so turn-key slushbox these days - you could earn a reasonable consulting fee guiding noobs through that

  2. Very informative article!
    I was just thinking about this a couple of days ago, considering where my current car would run and what would be a nice autocross-able car to upgrade to.

    Thanks DT, there goes the rest of my afternoon - and most of my weekend!

    1. Ok
      So, I'll need to run my Jetta TDI in HS Class... with Yugos!

      I knew my car was slow, but Yugos!


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